To answer, we must first know what RO/DI means. RO/DI is short for reverse osmosis / de-ionized water. These two filtration methods combine to form very pure water, which is vital for a healthy aquarium. Using this type of filtered water keeps aquarists from introducing heavy metals, chlorine, chloramine, silicates, phosphates, nitrates and any other possible contaminants that might be hiding in your water source. As a result, the final RO/DI water used in aquariums will result in better water quality, reduced stress on fish, and less algae problems. If you are having algae issues and do not use RO/DI water, then I would highly suggest investing in an unit or using a reputable aquarium maintenance company that uses high quality RO/DI water with their routine water changes and topoff water.
What is reverse osmosis?
Reverse osmosis is a type of water purification process that uses pressure to force feed water through a semi-permeable membrane. A semi-permeable membrane means that only some of the water is allowed to pass through the membrane. The smaller molecules (pure water) pass through the membrane while the larger molecules (heavier elements which cause contaminants) are forced through the waste line. A good, quality membrane will remove 95-99% of the impurities in your feed water (tap water.) Reverse osmosis water systems also typically use 3 or 4 prefilters. They help reduce the contaminants before the membrane. The prefilters (usually micron sediment and carbon cartridges) will help increase the life capacity of the membrane.
What is deionization?
Deionization is the second part of a RO/DI water system. It comes after the reverse osmosis membrane. The good water coming from the membrane will ideally be between 1 to 5 ppm TDS levels. A deionizer unit is added to the RO/DI system in order to get near 0 ppm. Water passes through the mixed bed resin in the deionizer cartridge. The resin exchanges positive hydrogen and negative hydroxyl molecules for positive and negative contaminant molecules in the water. As more water passes through the cartridge, the resin absorbs as much elements as it can hold. The cartridge will need new resin. This will reduce the impurities even more getting more pure water.
What else do I need to know about RO/DI systems?
Now we know how an RO/DI water purification system works and the answer to why use RO/DI water for aquariums. Reverse osmosis is very pure water. The water that goes through this type of filtration is stripped of all the elements, both good and bad. If you are using RO/DI for a freshwater aquarium, then it is a good idea to add some of those beneficial trace elements back to the water. I recommend RO Right by Kent and prefer the powder form myself. Also depending on your water source, RO/DI units typically soften the water. If hard water is what you’re after, then you might want to add a pH adjuster. Saltwater aquariums use RO/DI water mixed with marine salt. The sea salt, Instant Ocean, has trace elements found in natural seawater.
In conclusion, if you want to provide the best environment for your aquatic creatures, then RO/DI water is the best way to go. If I’m investing time and money into my aquarium, I want to use the purest water I can find to be successful in my fish keeping. Since your aquarium’s main ingredient is water, it makes sense to provide good quality h20. Find out more about choosing the right RO/DI water system to fit your needs.